The present invention relates generally to impact absorbing structures for vehicle steering systems, and more particularly to support and release mechanisms for tilt pivots of tilt steering columns.
When a tilt steering system has an impact absorbing structure by being provided with a steering column and a steering shaft which are coaxially coupled to each other and have an axially collapsible structure, a tilt pivot of a tilt rotation is enough supported by being rotatably coupled with a hinge to a lower bracket (nearer to a steering gear) rigidly attached to a vehicle body.
On the other hand, when a tilt steering system is provided with a steering column and a steering shaft which are coaxially coupled to each other and do not have an axially collapsible structure, that is, have a rigid structure against compression, a tilt pivot of a tilt rotation can not be supported in the same way. If the tilt pivot is rotatably coupled with a hinge to a lower bracket rigidly attached to the vehicle body, an impact can not be absorbed by releasing the steering column from the lower bracket even while the steering column can be otherwise released from an upper bracket at the impact. The lower bracket may be applied with the same structure of the upper bracket to provide a release mechanism. This structure however raises a product cost.
Accordingly, a tilt rotation and an axially collapse are provided by coupling a steering column to a lower bracket with a support pin and a simple slot. One such tilt steering system has been disclosed in Japanese Utility Model Provisional Publication No. 62-23771 (Kinoshita) published Feb. 13, 1987 (hereinafter is referred to as “JP62-23771”).